Milk-added coffee beverage

ABSTRACT

The present invention provides an economical process for producing a milk-added coffee beverage with an enhanced flavor in a process for producing a milk-added coffee beverage produced through a step of heat sterilization of coffee and milk component as the main raw materials; comprising adding a strongly basic substance and/or basic amino acid to coffee component and conducting the heat sterilization after milk component is admixed to the coffee component; whereby coagulation at the step of admixing milk component is prevented and precipitation which tends to arise after the heat sterilization is prevented with the use of much smaller amount of emulsifier and thickening agent.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a milk-added coffee beverageproduced through a step of heat sterilization using coffee and milkcomponent as the raw materials, and to a process for producing it. Morespecifically, it relates to a stable and rich-flavored milk-added coffeebeverage in which precipitation that occurs after heat sterilizationtreatment is prevented, and to a process for producing it.

[0002] A wide variety of milk-added coffee beverage products (hereunderreferred to as “milk-added coffee beverages”) are known that areproduced through a step of heat sterilization using coffee and milkcomponents as the raw materials, and when classified according to thetype of container these include canned beverages, PET bottled beverages,cardboard packed beverages and the like.

[0003] The common production steps for milk-added coffee beverages, inthe case of canned milk-added coffee beverages for example, are“roasting”, “grinding”, “extraction”, “formulation”, “filtration”,“filling”, “rolling”, “sterilization”, “refrigeration” and “casepacking”.

[0004] The “formulation” step is a critical step in terms of the qualityof product in the milk-added coffee beverage production process.Specifically, when milk is directly added to coffee extract, the acidicpH of the coffee extract causes the milk to coagulate. It has beencommon in the past to add sodium bicarbonate to milk-added coffeebeverages in order to prevent milk coagulation. Sodium bicarbonate isused because it is colorless and odorless, and has little effect onflavor.

[0005] The “sterilization” step is also a critical step in terms of thequality of product in the milk-added coffee beverage production process.In the sterilization step, heat sterilization is usually carried out for20 minutes in a 250 g can at 125° C. (“Food Production/Distribution DataHandbook”, Japan Industry Research Institute Publication Center, p.720).However, milk-added coffee beverages tend to produce precipitation afterheat sterilization, and although such precipitation poses no problemwhatsoever in terms of the safety of the product, it considerablyimpairs the product value.

[0006] Adjustment in the amount of sodium bicarbonate added has been acommon means used to prevent these problems, but this alone does notprovide a sufficient anti-precipitation effect, and therefore additionof an emulsifier or thickening agent (stabilizer, thickener, etc.) hasbeen necessary. However, while addition of an emulsifier or thickeningagent provides an anti-precipitation effect, it is sometimes undesirablefrom the standpoint of the flavor of the milk-added coffee beverage, andhas also raised the product cost. In addition, since a greater amount ofcoffee and milk components tends to result in easier precipitation afterheat sterilization, it is necessary to increase the amount of emulsifieror thickening agent, and this has led to problems of further flavorimpairment or cost increase. Depending on the formulation, even additionof an emulsifier or thickening agent fails to provide a sufficientanti-precipitation effect in many cases.

[0007] Japanese Unexamined Patent Publication HEI No. 7-184546 disclosesa process for producing a stable coffee beverage which is characterizedby subjecting a coffee extract to both treatment with mannanase andaddition of alkali sodium or potassium salts, and particularly sodiumbicarbonate.

[0008] Also, Japanese Unexamined Patent Publication HEI No. 8-228686discloses a method of preventing precipitation of milk-added cannedcoffee which is characterized by adding a mixed emulsifier comprising acombination of emulsifiers each with a different HLB(hydrophilic-lipophilic balance).

[0009] In addition, Japanese Unexamined Patent Publication HEI No.11-313647 discloses a method of preventing precipitation of milk-addedcanned coffee which is characterized by alkali-treating roasted coffeebeans before extraction.

[0010] These methods all have their respective features, but an evensimpler, more economical method has been desired.

SUMMARY OF THE INVENTION

[0011] It is therefore an object of the present invention to provide aneconomical method for preventing precipitation in milk-added coffeebeverages during admixture of the milk and after heat sterilization.

[0012] It is another object of the invention to provide a rich-flavoredmilk-added coffee beverage wherein precipitation during admixture ofmilk component and after heat sterilization is prevented.

[0013] It is yet another object of the invention to provide a milk-addedcoffee beverage which is prepared by a process for production ofmilk-added coffee beverages involving heat sterilization after admixtureof the milk component, wherein a strongly basic substance and/or a basicamino acid is added before admixture of the milk component, in order toprevent precipitation during admixture of the milk and after the heatsterilization, and to reduce the amount of emulsifier or thickeningagent added which has been a cause of reduced flavor, as well as aprocess for its production.

[0014] The invention may be applied with particular advantages inproducts having a high content of coffee and milk components, to preventprecipitation after heat sterilization without increasing the amount ofadded emulsifier or thickening agent.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a graph showing the relationship between the amount ofsodium bicarbonate added (pH) and the degree of precipitation after heatsterilization, for an emulsifier-free canned milk-added coffee beverage.

[0016]FIG. 2 is a bar graph showing the degree of precipitation afterheat sterilization with addition of both sodium bicarbonate anddifferent pH adjusters in emulsifier-free canned milk-added coffeebeverages.

[0017]FIG. 3 is a graph showing the relationship between the amount ofstrongly basic substance added (pH) and the degree of precipitationafter heat sterilization, for an emulsifier-free canned milk-addedcoffee beverage.

[0018]FIG. 4 is a bar graph showing the degree of precipitation afterheat sterilization with addition of basic amino acids in emulsifier-freecanned milk-added coffee beverages.

DETAILED DESCRIPTION OF THE INVENTION

[0019] As a result of extensive research into the cause of precipitationin milk-added coffee beverages after heat sterilization, for the purposeof solving the problems described above, the present inventors found,surprisingly, that sodium bicarbonate that has conventionally been usedfor pH adjustment to prevent coagulation during the milk-mixing step isthe major cause of precipitation during the heat sterilization step.Upon examining the mechanism of precipitation due to sodium bicarbonate,it was determined that precipitation of coffee and milk occurs becauseof a salting-out reaction due to sodium bicarbonate.

[0020] The present inventors then tried replacing all or a portion ofthe sodium bicarbonate with strongly basic substances and/or basic aminoacids, and completed the present invention upon determining that thiscan prevent coagulation during admixture of milk component and preventprecipitation after heat sterilization.

[0021] When using a strongly basic substance or a basic amino acid in amilk-added coffee beverage according to the invention, there is noadverse effect on the color, odor or taste, similar to sodiumbicarbonate. In fact, it is possible to reduce or eliminate the additionof emulsifier or thickening agent, which has been a cause of impairedflavor, and thereby produce a milk-added coffee beverage with a moresatisfactory flavor than conventional coffee beverages. A particularlynotable difference in flavor over the prior art method is achieved whensubstantially no sweetener component is added, so that a beverageexhibiting the original satisfactory flavor of milk-added coffeebeverages may be obtained together with an anti-precipitation effect.

[0022] The present invention will now be explained in detail.

[0023] According to the present invention, “milk-added coffee beverage”refers to a beverage product prepared using coffee and milk componentsas the main raw materials, through a step of heat sterilization. Thetype of product is not particularly restricted, but mainly intended are“coffee”, “coffee beverages” and “coffee-added soft drinks” as definedby the “Fair Competition Guidelines on Labeling of Coffee and OtherBeverages” established in 1977. Beverages prepared from coffee as theraw material and having a milk solid content of at least 3.0% by weightfall under the “Fair Competition Guidelines on Labeling of DrinkingMilk” and are treated as “milk beverages”, but for the purpose of thepresent invention these will also be included as milk-containing coffeebeverages.

[0024] “Coffee component” refers to a solution containing coffeebean-derived components, of which there may be mentioned primarilycoffee extracts, i.e., solutions obtained by extraction of roasted andground coffee beans using cold or hot water. There may also bementioned, as coffee component, coffee solutions prepared fromconcentrated coffee extract, soluble coffee obtained by drying coffeeextract, or the like, with suitable amounts of cold or hot water.

[0025] The cultivated species of coffee bean used as the raw material isnot particularly restricted, and there may be mentioned species such asArabica, Robusta, Liberica and the like, while the variety is also notparticularly restricted, and there may be mentioned Mocha, Brazil,Colombian, Guatemala, Blue Mountain, Kona, Mandelin, Kilimanjaro and thelike.

[0026] There are no particular restrictions on the degree of roasting(represented by the 3 basic levels of light roasted, medium roasted anddark roasted, in that order), and raw coffee beans may also be used.Coffee beans of two or more varieties may also be used in a blend.

[0027] There are also no particular restrictions on the degree ofgrinding of the roasted coffee beans (classified into coarse grinding,medium grinding, fine grinding, etc.), and ground coffee of differentparticle size distributions may be used, while the extraction may becarried out with any of various types of extractors (drip type, siphontype, boiling type, jet type, continuous type, etc.) using cold water,hot water or the like. A higher extraction temperature for the roastedcoffee beans and a higher degree of extraction of the coffee componentwill tend to promote precipitation after heat sterilization, but thereare no particular restrictions on the temperature conditions or degreeof extraction.

[0028] The content of coffee component in the milk-added coffee beverageis not particularly restricted, but is preferably 0.1-10 wt% in terms ofsolid portion. Here, “solid portion” refers to the weight of the drymaterial obtained after drying the coffee component by a common dryingmethod (lyophilization, evaporation to dryness, etc.) to remove themoisture.

[0029] In the present invention, “milk component” refers to a componentadded to a coffee beverage in order to impart milk flavor or milktexture, and includes primarily any milk, cow milk or dairy products. Asexamples there may be mentioned raw milk, cow milk, special cow milk,partially defatted milk, skim milk, processed milk, milk beverages andthe like, and as dairy products there may be mentioned cream,concentrated whey, concentrated milk, concentrated skim milk, sugar-freecondensed milk, sweetened condensed skim milk, total milk powder, skimmilk powder, cream powder, whey powder, buttermilk powder, modified drymilk and the like. Cow milk is preferably used from the standpoint offlavor. Fermented milk or lactic acid bacteria beverages may also beused in the form of powders.

[0030] The content of milk component in the milk-added coffee beverageis not particularly restricted, but is preferably 0.1-10 wt% in terms ofsolid portion. Here, “solid portion” refers to the weight of the drymaterial obtained after drying the milk component by a common dryingmethod (lyophilization, evaporation to dryness, etc.) to remove themoisture.

[0031] In the present invention, a “strongly basic substance” is asubstance such as a base or salt that is alkaline with a degree ofelectrolytic dissociation (α) of nearly 1 when dissolved in water. Avalue of α>0.9 is preferred. The degree of electrolytic dissociation (α)is the proportion of the amount (moles, number of molecules) of ionizedsolute, where α=1 denotes complete ionization, or 100% ionization. Asstrongly basic substances there may be mentioned sodium hydroxide,sodium hydroxide solution, potassium hydroxide, potassium hydroxidesolution, trisodium phosphate, tripotassium phosphate and the like.

[0032] The amount of strongly basic substance to be added is notparticularly restricted, but is preferably 0.005-0.5 wt% inconsideration of the effect and cost. However, it is preferably added inan amount such that the pH of the milk-added coffee beverage does notrise above approximately 8.0 after its addition.

[0033] Of the strongly basic substances according to the invention,sodium hydroxide, (including sodium hydroxide solution), potassiumhydroxide (including potassium hydroxide solution), trisodium phosphateand tripotassium phosphate are all food additives and are suitable foruse from the standpoint of safety. These are available as commercialproducts in either solid or aqueous solution form. The purity is notparticularly limited so long as it is of a degree suitable forconsumption, and for example, the crystal sodium hydroxide purity may be70.0-75.0%, the sodium hydroxide anhydrate purity may be 95.0% orgreater and the potassium hydroxide purity may be 85.0% or greater. Thecrystallized form may be powdered, granular, globular, flaky,rod-shaped, etc. and is not particularly restricted.

[0034] In the invention, a “basic amino acid” is an amino acid thatexhibits basicity in aqueous solution, and there may be mentioned lysine(Lys), arginine (Arg) and histidine (His). Salts, such as alkali metalsalts or alkaline earth metal salts, or derivatives thereof which arebasic and suitable for consumption, are also included in the basic aminoacids of the invention.

[0035] The amount of the basic amino acid to be added is notparticularly restricted, but is preferably 0.01-1 wt% in considerationof effect and cost. Here it is also limited to an amount such that thepH of the milk-added coffee beverage does not rise above approximately8.0 after addition.

[0036] Of the basic amino acids of the invention, lysine (L-lysine),arginine (L-arginine) and histidine (L-histidine) are all food additivesand are suitable for use from the standpoint of safety. These areavailable as commercial products in either solid or aqueous solutionform, and their purity is not particularly restricted.

[0037] The strongly basic substance and/or basic amino acid of theinvention may be added at appropriate amounts in various combinationswithin a range that does not impair the anti-precipitation effect orflavor.

[0038] The strongly basic substance or basic amino acid is preferablyadded in a step after extraction of the coffee, i.e., before admixtureof the milk component, but it may instead be preadded to the cold or hotwater used for the coffee extraction step.

[0039] The pH of the milk-added coffee beverage product is notparticularly restricted, but in consideration of the object of theinvention and the flavor of the beverage, the pH is preferably 5.8-7.0for the product after heat sterilization.

[0040] According to the invention, by using a strongly basic substanceand/or basic amino acid instead of sodium bicarbonate it is possible toreduce the amount of addition of emulsifier or thickening agent, whichis a cause of impaired flavor of milk-added coffee beverages. An“emulsifier” in the present invention is any additive with anemulsifying effect, which is a surfactant in the wide sense. As examplesthere may be mentioned sucrose fatty acid esters, sorbitan fatty acidesters, polyglycerin fatty acid esters and the like. A “thickeningagent” is any additive with a thickening, gelling or stabilizingfunction, and there may be mentioned thickeners such as xanthan gum,gelling agents such as carrageenan, and stabilizers. In other words,emulsifiers and/or thickening agents include all those commonly used toprevent precipitation that occurs primarily during the heatsterilization step during production of milk-added coffee beverages andin the subsequent distribution, storage and vending machine warming.

[0041] Although an emulsifier or thickening agent is preferably used inthe beverage of the invention in order to supplement theanti-precipitation effect, it is important for an amount added to berestricted to a range that does not notably impair flavor; and anyemulsifiers and thickening agents are preferably added in a total amountof no greater than 1 wt%. For example, sucrose fatty acid esters areoften also used to prevent proliferation of heat-resistant bacteria, andthey may be added in a range that does not notably impair flavor. Anemulsifier or thickening agent may be added at any point with noparticular restrictions, so long as it is added no later thanimmediately following the start of the heat sterilization.

[0042] Sodium bicarbonate may be added to the beverage of the inventionin order to complement the anti-precipitation effect during admixture ofthe milk component, but it is important for it to be in a range thatdoes not promote precipitation after heat sterilization, and the amountis preferably no greater than 0.14 wt%.

[0043] A “sweet component” according to the invention is any componentthat exhibits sweetness. As examples, there may be mentioned sucrose,isomerized glucose, glucose, fructose, lactose, maltose, xylose,isomerized lactose, fructooligosaccharide, maltooligosaccharide,isomaltooligosaccharide, galactooligosaccharide, coupling sugar,paratinose, maltitol, sorbitol, erythritol, xylitol, lactitol,palatinit, reduced thickening agent sugar, stevia, glycyrrhizin,thaumatin, monellin, aspartame, alitame, saccharin, acesulfame K,sucralose, dulcin, and the like.

[0044] The presence, amount of addition and the point of addition of thesweet component may be appropriately adjusted according to the designedproduct, and are not particularly restricted. For an enhancement offlavor, it is a preferred mode of the invention to either add no sweetcomponent or substantially no sweet component or to only lightly sweetenthe product, since this will allow the tongue to sense the originalflavor of the coffee with no influence of sweetening.

[0045] Other components may also be added, as appropriate, to impart tothe beverage of the invention the necessary or preferred properties as amilk-added coffee beverage. As other components there may be mentionedantioxidants, (sodium erythorbate, etc.), aromatics (coffee flavorings,milk flavorings, etc.) and water (ion-exchange water, purified water,natural water, etc.).

[0046] According to the invention, the heat sterilization method mayinvolve retort sterilization, a hot pack, sterile packing or the likeand is not particularly restricted; while the sterilization conditionsmay be appropriately determined depending on the properties of thecontents, the container, etc.

[0047] There are no particular restrictions on the shape of thecontainer for the milk-added coffee beverage, and it may be canned, PETbottled, glass bottled, cardboard packed, etc.

EXAMPLES

[0048] The invention will now be explained in greater detail by way ofexamples, with the understanding that the invention is in no wayrestricted to the examples.

Reference Example

[0049] The relationship between the amount of sodium bicarbonateaddition and the degree of precipitation after heat sterilization wasexamined under conditions with no emulsifier or thickening agentaddition.

[0050] Sodium bicarbonate was added in different amounts to a coffeeextract (pH: approximately 5.0) obtained by extraction of 12 g ofroasted coffee beans with purified water at 90° C., and then 12 g ofsugar and 16 ml of cow milk were added to obtain test solutions whichwere each adjusted to a total of 200 ml with purified water.

[0051] The amount of sodium bicarbonate addition was determined in thefollowing manner. For this test it was necessary to avoid precipitationduring addition of the cow milk (pH: approximately 6.6). Considering theisoelectric point of casein which constitutes half of the protein in cowmilk (near a pH of approximately 4.6), the addition of sodiumbicarbonate was set to the minimum giving a pH of 6.0 or greater beforethe cow milk addition for all of the test solutions (a finalconcentration of 0.33 g/L). Also, considering the pH range in which mostmilk-added coffee beverage products are distributed (a pH range ofapproximately 6.0-6.5, see arrow in FIG. 1), the amounts of sodiumbicarbonate were set to final concentrations of 0.33, 0.50, 0.67, 0.83,1.00, 1.17, 1.33, 1.67 and 2.00 g/L.

[0052] The obtained test solutions were filled into 190 g cans andsubjected to heat sterilization (125° C., 20 minutes) to obtain cannedmilk-added coffee beverages without addition of emulsifier.

[0053] The degree of precipitation of each of the canned milk-addedcoffee beverages was then measured by the following method.Specifically, the canned milk-added coffee beverage was allowed to standat room temperature for 3 hours and agitated, after which 10 ml thereofwas sampled and dispensed into a graduated centrifugation tube andcentrifuged at 3000 rpm for 10 minutes, and the volume of theprecipitate was measured.

[0054] The results of the experiment are shown in FIG. 1. The horizontalaxis represents the pH values of the (sterilized) canned milk-addedcoffee beverages after addition of sodium bicarbonate at differentconcentrations (with a larger amount of sodium bicarbonate additionresulting in a higher pH).

[0055] As can be clearly seen from FIG. 1, under the pH conditions ofthis test which included the pH range in which most coffee beverageproducts are distributed (a pH range of approximately 6.0-6.5, or interms of addition of sodium bicarbonate, approximately 0.67-1.67 g/L;see arrow in FIG. 1), a strict correlation was found between the pHafter heat sterilization (i.e. the amount of sodium bicarbonateaddition) and the degree of precipitation after heat sterilization. Thedegree of precipitation reached an acceptable level of under 0.1 ml/10ml, depending on the amount of sodium bicarbonate addition (see pH rangeof approximately 6.0-6.2 in FIG. 1).

[0056] However, considering the fact that chemical changes duringstorage cause slight variation in the pH of milk-added coffee beverages,and the need to adapt to various product designs based on flavor, shelflife, etc., a technique is required that can prevent precipitation underany pH condition in the pH range of approximately 6.0-6.5 as the endproduct. The results of this test demonstrated that addition of sodiumbicarbonate alone, under conditions where no emulsifier or thickeningagent is added, can only be successfully applied in the limited pH rangementioned above.

Example 1

[0057] The use of sodium bicarbonate with different pH adjustors wasexamined. Sodium bicarbonate was added to coffee extract in a fixedamount, using the amount which produced the least precipitation in theexperiment of the Reference Example (final concentration: 0.83 g/L,product pH: 6.2) (for a pH of 6.5 at this stage), and then different pHadjustors were added in amounts giving the same pH (pH 6.8). Theprocedure thereafter was carried out according to the Reference Exampleto obtain canned milk-added coffee beverages.

[0058] Strongly basic substances (sodium hydroxide, potassium hydroxide)and weakly basic substances (disodium hydrogen phosphate, dipotassiumhydrogen phosphate, sodium bicarbonate (positive control)) were used asthe pH adjustors. Separately, a solution was prepared with purifiedwater added instead of a pH adjustor, as a negative control. The degreeof precipitation in each of the canned milk-added coffee beverages wasmeasured using the same method as in the Reference Example.

[0059] The results of this experiment are shown in FIG. 2. The pH valuesof the canned milk-added coffee beverages fell after heat sterilization.For example, the test product to which sodium bicarbonate was added inthe amount (0.83 g/L) which gave the lowest degree of precipitation hada pH of 6.2 (see FIG. 1), but its pH was 6.5 before heat sterilization.This was thought to be due to a chemical change in the components byheating, and it is a phenomenon often seen upon heat sterilization ofbeverages.

[0060] As can be clearly seen from FIG. 2, the degree of precipitationchanged significantly depending on the type of pH adjustor.Specifically, when a strongly basic substance (sodium hydroxide orpotassium hydroxide) was added, the degree of precipitation was about aslow as the negative control (purified water). On the other hand, when aweakly basic substance (disodium hydrogen phosphate, dipotassiumhydrogen phosphate or sodium bicarbonate (positive control)) was added,the degree of precipitation was greater than when a strongly basicsubstance was added.

[0061] It was thus demonstrated that to control precipitation ofmilk-added coffee beverages during heat sterilization, it is effectiveto replace a portion of the sodium bicarbonate used as a pH adjustorwith a different pH adjustor, and particularly that the use of astrongly basic substance such as sodium hydroxide or potassium hydroxideis important.

Example 2

[0062] Based on the knowledge obtained from Example 1, all of the sodiumbicarbonate was replaced with a strongly basic substance (sodiumhydroxide in this case). In the same manner as the Reference Example,the sodium hydroxide concentration was added in different amounts toobtain canned milk-added coffee beverages with no emulsifier added. Theresults of the experiment are shown in FIG. 3.

[0063] As can be clearly seen from FIG. 3, when all of the sodiumbicarbonate was replaced with a strongly basic substance, a notableeffect of preventing precipitation was found in the pH range in whichcommon milk-added coffee beverage products are distributed (a pH rangeof approximately 6.0-6.5, see arrow in FIG. 3).

[0064] It was thus demonstrated that to control precipitation ofmilk-added coffee beverages during heat sterilization, it is effectiveto use a strongly basic substance alone as the pH adjustor. It was alsodemonstrated that using a strongly basic substance as the pH adjustorcan prevent precipitation during heat sterilization under any pHcondition in the pH range of approximately 6.0-6.5 as the end product.

Example 3

[0065] A test sample of a milk-added coffee beverage (emulsifier-free)was prepared by mixing the raw materials in the prescribed amounts shownin Table 1, heat sterilizing and adding a strongly basic substance, andthe degree of precipitation and flavor were evaluated (Test Product 1).Two control test samples of sodium bicarbonate-containing milk-addedcoffee beverages (Control Product 1-1: emulsifier-free product andControl Product 1-2: emulsifier-added product) were also prepared. Anemulsifier (sucrose fatty acid ester) was added to Control Product 1-2in the necessary amount as an anti-precipitation agent.

[0066] Table 2 shows the evaluation results for the degree ofprecipitation and the flavor. The degree of precipitation was measuredaccording to the Reference Example. The flavor was evaluated as theaverage of score by five professional panelists. Scoring was on thefollowing 5 levels: “Good”=5 points, “Fair”=4 points, “Ordinary”=3points, “Somewhat poor”=2 points, “Poor”=1 point.

[0067] The results are shown in Table 2. The flavor evaluation score forTest Product 1 (sodium bicarbonate-added, emulsifier-free) was fair at4.2, but the degree of precipitation was 0.70 ml/10 ml, which wasconsiderably greater than the target value (≦0.1 ml/10 ml).

[0068] With Control Product 1-2 (sodium bicarbonate-added,emulsifier-added), the effect of adding the emulsifier reduced thedegree of precipitation to 0.05 ml/10 ml which was an acceptable level(less than 0.1 ml/10 ml). However, the flavor evaluation score (3.0) waslower than that of the other two products (4.2-4.6), suggesting thataddition of the emulsifier led to a reduction in flavor.

[0069] On the other hand, the degree of precipitation with ControlProduct 1 was at an acceptable level of 0.05 ml/10 ml (less than 0.1ml/10 ml), while the flavor evaluation score of 4.6 was the highestevaluation among the three products. This indicates that precipitationwas successfully inhibited without using an emulsifier that causesreduction in flavor.

[0070] Thus, by using the present invention which employs a stronglybasic substance as the pH adjustor, it is possible to inhibitprecipitation during heat sterilization and produce a milk-added coffeebeverage with a satisfactory taste. TABLE 1 Control Control Test Product1-1 Product 1-2 Product 1 Coffee beans 60 g 60 g 60 g Sugar 60 g 60 g 60g Sodium bicarbonate 2.0 g 2.0 g 0 g Sodium hydroxide 0 g 0 g 0.4 gEmulsifier 0 g 1.5 g 0 g Cow milk 120 ml 120 ml 120 ml Total (adjustedwith water) 1000 ml 1000 ml 1000 ml

[0071] TABLE 2 Control Control Test Product 1-1 Product 1-2 Product 1Degree of precipitation 0.70 0.05 0.05 (ml/10 ml) Average score of 4.2 3.0  4.6  flavor evaluation

Example 4

[0072] Next, basic amino acids were examined as additives expected toprovide an anti-precipitation effect, in addition to the strongly basicsubstances which were confirmed to have a high anti-precipitationeffect.

[0073] Emulsifier-free canned milk-added coffee beverages were obtainedin the same manner as the Reference Example, but using only a basicamino acid (arginine or histidine) as the pH adjustor. As a control, atest sample of an emulsifier-free canned milk-added coffee beverage wasobtained using only sodium bicarbonate as the pH adjustor. The resultsof the experiment are shown in FIG. 4.

[0074] As can be clearly seen from FIG. 4, the degree of precipitationwas an acceptable level (≦0.1 ml/10 ml) when using either basic aminoacid, and much lower than sample using sodium bicarbonate as the pHadjustor. The method of using a basic amino acid as the pH adjustor wasthus demonstrated to be useful for inhibiting precipitation during heatsterilization of milk-added coffee beverages.

Example 5

[0075] Raw materials were combined in the prescribed amounts shown inTable 3 and heat sterilized, and then a strongly basic substance wasadded to prepare a milk-added coffee beverage (emulsifier-free) as acoffee- and cow milk-augmented type test product, and the degree ofprecipitation and flavor were evaluated. As a control, a coffee- and cowmilk-augmented type test product was prepared by adding sodiumbicarbonate to a milk-added coffee beverage (emulsifier-added). Anemulsifier (sucrose fatty acid ester) was added thereto in the necessaryamount as an anti-precipitation agent.

[0076] The degree of precipitation was measured according to theReference Example, and the flavor evaluation was carried out accordingto Example 3. Table 4 shows the degrees of precipitation and the resultsof the flavor evaluation. TABLE 3 Control Test Product 2 Product 2Coffee beans 75 g 75 g Sugar 60 g 60 g Sodium bicarbonate 2.5 g 0 gSodium hydroxide 0 g 0.5 g Emulsifier 3.0 g 0 g Cow milk 150 ml 150 mlTotal (adjusted with water) 1000 ml 1000 ml

[0077] TABLE 4 Control Product 2 Test Product 2 Degree of precipitation0.07 0.06 (ml/10 ml) Average score of 2.8  4.6  flavor evaluation

[0078] As shown in Table 4, the degree of precipitation of Test Product2 was at an acceptable level (<0.1 ml/10 ml), equivalent to that ofControl Product 2. However, the flavor evaluation of Test Product 2 washigher than that of the control product. It is presumed that with thehigh coffee and cow milk content in Control Product 2, the flavorevaluation was unsatisfactory because of the increase in emulsifiernecessary to prevent precipitation after heat sterilization, whereaseven with a high coffee and cow milk content in the Test Product 2, asatisfactory flavor evaluation was obtained because precipitation afterheat sterilization was successfully prevented without addition of anemulsifier.

Example 6

[0079] A test sample of a milk-added coffee beverage (emulsifier-free)containing both a strongly basic substance and a basic amino acid wasprepared by mixing the raw materials in the prescribed amounts shown inTable 5 and heat sterilizing.

[0080] As a result, the degree of precipitation of Test Product 3 was atan acceptable level (≦0.1 ml/10 ml), and the flavor evaluation wassatisfactory.

[0081] Thus, by using the present invention which employs a basic aminoacid as the pH adjustor, it is possible to inhibit precipitation duringheat sterilization and produce a milk-added coffee beverage with asatisfactory taste. TABLE 5 Test Product 3 Coffee beans 60 g Sugar 60 gSodium hydroxide 0.2 g Arginine 0.6 g Cow milk 120 ml Total (adjustedwith water) 1000 ml

Example 7

[0082] The effect of the invention when adding no sweet components wasevaluated.

[0083] A milk-added coffee beverage (emulsifier-free) containing nosweet component, using a strongly basic substance as the pH adjustor,was prepared as a test sample with the raw materials in the prescribedamounts shown in Table 6, and the degree of precipitation and flavorwere evaluated. A test product of a milk-added coffee beverage(emulsifier-added) containing no sweet component and using sodiumbicarbonate as the pH adjustor was also prepared as a control. Anemulsifier (sucrose fatty acid ester) was added thereto in the necessaryamount as an anti-precipitation agent.

[0084] The degree of precipitation was measured according to theReference Example, and the flavor evaluation was carried out accordingto Example 3. Table 7 shows the degrees of precipitation and the resultsof the flavor evaluation. TABLE 6 Control Test Product 4 Product 4Coffee beans 60 g 60 g Sodium bicarbonate 2.0 g 0 g Sodium hydroxide 0 g0.4 g Emulsifier 2.5 g 0 g Cow milk 120 ml 120 ml Total (adjusted withwater) 1000 ml 1000 ml

[0085] TABLE 7 Control Product 4 Test Product 4 Degree of precipitation0.06 0.05 (ml/10 ml) Average score of 2.3  4.8  flavor evaluation

[0086] As a result, the degree of precipitation of the test product andof the control product were both equivalent at an acceptable level (≦0.1ml/10 ml). However, the flavor evaluation of the test product was higherthan that of the control product. The difference in the flavorevaluations of both products was greater than in the previous test(Example 3) in which sweetness was added. It is presumed that when nosweet component is added, the flavor can be judged without the influenceof sweetness, allowing a more definite distinction between rich and poorflavor.

[0087] Thus, the present invention can be suitably used when the flavoris to judged without the influence of sweetness, such as in cases withsubstantially no addition of sweet components or with only lightsweetening.

What is claimed is:
 1. A milk-added coffee beverage characterized bybeing prepared by adding a strongly basic substance and/or a basic aminoacid to coffee component, mixing milk component therewith and then heatsterilizing the mixture.
 2. A milk-added coffee beverage according toclaim 1, characterized in that the strongly basic substance and/or basicamino acid is added before mixture with milk component.
 3. A milk-addedcoffee beverage according to claim 1 or 2, wherein addition of thestrongly basic substance and/or basic amino acid prevents precipitationafter the heat sterilization.
 4. A milk-added coffee beverage accordingto any one of claims 1 to 3, wherein addition of the strongly basicsubstance and/or basic amino acid reduces the amount of emulsifierand/or thickening agent required.
 5. A milk-added coffee beverageaccording to any one of claims 1 to 4, wherein the pH of the milk-addedcoffee beverage product is 5.8-7.0.
 6. A milk-added coffee beverageaccording to claim 5, wherein the total amount of emulsifier andthickening agent added is no greater than 1 wt%.
 7. A milk-added coffeebeverage according to any one of claims 1 to 6, wherein the stronglybasic substance is at least one selected from the group consisting ofsodium hydroxide, potassium hydroxide, trisodium phosphate andtripotassium phosphate.
 8. A milk-added coffee beverage according toclaim 7, wherein the amount of the strongly basic substance added is0.005-0.5 wt%.
 9. A milk-added coffee beverage according to any one ofclaims 1 to 8, wherein the basic amino acid is at least one selectedfrom the group consisting of lysine, arginine and histidine.
 10. Amilk-added coffee beverage according to claim 9, wherein the amount ofthe basic amino acid added is 0.01-1 wt%.
 11. A milk-added coffeebeverage according to any one of claims 1 to 10, wherein the amount ofsodium bicarbonate added is no greater than 0.14 wt%.
 12. A milk-addedcoffee beverage according to any one of claims 1 to 11, which containscoffee component at 0.1-10 wt% in terms of solid portion.
 13. Amilk-added coffee beverage according to any one of claims 1 to 12, whichcontains milk component at 0.1-10 wt% in terms of solid portion.
 14. Amilk-added coffee beverage according to any one of claims 1 to 13,characterized in that the milk component is cow milk.
 15. A milk-addedcoffee beverage according to any one of claims 1 to 14, characterized bycontaining substantially no sweet components or being only lightlysweetened.
 16. A process for producing a milk-added coffee beverageaccording to any one of claims 1 to
 15. 17. A process for producing amilk-added coffee beverage produced through a step of heat sterilizationof coffee component and milk component as the main raw materials,wherein a strongly basic substance and/or basic amino acid used as a pHadjuster is added prior to the heating step while sodium bicarbonate iseither not used at all or used at no greater than 0.14 wt%, to reducethe amount of emulsifier and/or thickening agent required and preventprecipitation by the heat sterilization, for production of arich-flavored milk-added coffee beverage.